On the Sense of Feeling. 291 



The dermis, cutis, or true skin, is a deuse, fibrous, vascular membrane, con- 

 taining and protecting the nerves, sanguinic capillaries, and ducts of the 

 part : it possesses firmness and strength sufficient to defend the body it in- 

 vests, but is supple enougli not to impede its movements. Its thickness is 

 very variable, but it almost always constitutes the greater portion of the 

 whole integument. The functions of the cutis are as important, and their 

 due discharge as nearly affects the well-being of the system, as those of 

 the lungs or intestinal canal. 



The upper layers of the dermis are very dense, the lower pass gradually 

 into cellular membrane. 



The dermis, when examined after long maceration in water, is found to 

 be composed of a great number of fibres, forming a sort of tissue, of 

 greater or less density according to circumstances ; and through the in- 

 terstices between which, the various ducts and vessels of the part are trans- 

 mitted, some of which, as the nerves and blood-vessels, ramify to such 

 minuteness, that the smallest prick cannot be received without giving pain 

 and drawing blood. The dermis is the seat of those furrows and wrinkles, 

 the absence of which forms one great feature in infantine beauty, while 

 their presence bestows dignity and a venerable aspect upon sorrow and age. 



The thickness of the dermis varies, as we have observed, in difTerent 

 parts of the body, being much thicker on the back than on the breast; an 

 observation applicable to most of the mammalia. Over some parts of the 

 body, as the lips and eyelids, the dermis is transparent. 



The dermis is of considerable value in the arts, and we are all of us 

 indebted to its preparations for many of the comforts which we enjoy. 



Leather is a compound of gelatine and vegetable matter, made by steeping 

 the dermis of animals in infusions of certain barks. The skins are first 

 steeped in lime water, frequently changed, on account of the minute por- 

 tion of that earth held by it in solution. By this means the epidermis and 

 hair are removed, and the dermis is ready for the second process. This 

 consists in jjermitting the skin to become more or less putrid, in order to 

 soften it. If at this stage, instead of being permitted to putrlfy, it be 

 boiled in water, it forms glue. When the hides intended for leather are 

 Bufliciently putrid, they are taken out, and submitted in the tan-pit to the 

 action of an astringent vegetable infusion, the strength of which is gradu- 

 ally augmented, until the skin is brown throughout; — imperfectly tanned 

 leather, shewing always a white streak in its centre. Formerly two years 

 was required, to ensure a due penetration of the astringent principle into 

 a thick hide : now, by a happy application of the air-pump, to exhaust the 

 air from the skins, and then of the hydraulic press, to force the infusion 

 into them, the thickest hides are tanned better than before, and in six 

 weeks or two months only ; so that the quality of the leather is improved, 

 and its cost diminished. 



Such is the dermis, the innermost layer of the integument, and such are 



